The porous material is a new type of engineering material with excellent properties, combining both functional and structural properties, which is widely used in fields of metallurgical machinery, petrochemical industry, energy and environmental protection, national defense and military industry, nuclear technology and biopharmaceuticals, medical equipment, etc. For example, the porous material can be used for energy absorption, shock damping and noise reduction, such as in automotive bumpers and voice filters; the porous material can be used for filtration and separation of gas or liquid, so as to achieve the purification and separation of medium; the porous material can be used in heat exchangers having high efficiency; the porous material such as nickel foam, copper foam can be used as excellent electrode material for a variety of batteries, fuel cells and solar cells; the porous material such as porous titanium, porous tantalum, porous hydroxyapatite can be used as biomaterials, such as artificial bones, tooth, etc; the porous ceramics can be used as a catalyst carrier to promote the reaction; rigid polyurethane foam plastic can be used as thermal insulation materials, widely used in building energy saving; polymeric foam is used as a radome and a housing of radio transmitter.
At present, the application demands for many porous materials to have a uniform structure. That is, the pore size and the distribution of the pores are uniform, so that the performance is uniform. However, in fact, many porous materials fail to meet the requirements due to the lack of uniformity. Although some materials assert achieving higher uniformity through improvement, but the uniformity is only at a large volume scale, if compared under a small volume scale, for example, a plurality of three-dimensional blocks with volumes less than or equal to one cubic centimeter are randomly selected to measure the mass, the degree of uniformity is still very large. That is, the current porous material are only uniform at a large volume scale, but not uniform at a small volume scale. It can also be said that the nonuniformity at a small volume scale of the porous material causes the nonuniformity of various properties of the porous material such as strength, elastic modulus. Therefore the true elastic modulus of porous materials cannot be effectively reduced, thus seriously affecting its function.